Control mechanism for rotatable shafts



Oct. 12, 1965 c. E. ADLER CONTROL MECHANISM FOR ROTATABLE SHAFTS 4 sheet-sheet 1 Filed Dec. 4, 1961 .www

INVENTOR. CLARENCE E. ADLER ATTORNEYS Oct. 12, 1965 c. E. ADLER 3,211,020

CONTROL MEGHANISM FOR ROTATABLE SHAFTS Filed Dec. 4, 1961 4 Sheecs-Shee'rl 2 INVENTOR. CLARENCE E. ADLER AT'ToRNEYs Oct. 12, 1965 c. E. ADLER CONTROL MECHANISM FOR ROTATABLE SHAFTS 4 Sheets-Sheet 5 Filed Dec. 4, 1961 INVEN TOR. CLARENCE E. ADLER VL B ATTORNEYS Oct. 12, 1965 c. E. ADLER 3,211,020

CONTROL MEOHANISM FOR ROTATABLE sHAFTs Filed Dec. 4, 1961 4 Sheets-Sheet 4 Figio INVENTOR. CLARENCE E. ADLER ATTORNEYS United States Patent O "ice 3,211,020 CONTROL MECHANISM FOR ROTATABLE SHAFTS Clarence E. Adler, Toledo, Ohio, assignor to Toledo Scale Corporation, Toledo, Ohio, a corporation of Ohio Filed Dec. 4, 1961, Ser. No. 156,626 Claims. '{Cl. 74-527) This invention relates to control mechanism for rotatable shafts.

The control mechanism is particularly well suited for controlling the operation of hand operated shafts such as are found in hand operated printers. United States Patent No. 2,922,361 issued on January 26, 1960 to C. E. Adler and G. T. Gray discloses a motor operated printer which in certain locations and uses is hand operated. The main drive shaft in such printer must be turned relatively slowly in order to give the several mechanisms in the printer time to complete their cycles, must be turned through exactly one revolution in order to complete a printing cycle but not to go beyond completion, must be locked at the end of each printing cycle, must be unlocked at the start of each printing cycle, and must not be turned backward at any time during its forward driving movement. In the past, no means has been provided for so controlling shafts that they will be operable satisfactorily in the manner described above in connection with the printer main drive shaft.

Accordingly, the objects of this invention are to provide means for turning a shaft through a multiple of a number of degrees after which automatic lock-up occurs, for turning a shaft relatively slowly through a multiple of a number of degrees after which automatic lock-up occurs, for automatically locking a shaft at the end of a turning cycle, for readily unlocking a locked shaft at the start of a turning cycle, for preventing by improved means backward rotation of a shaft during a forward movement, and to improve the operation of hand operated mechanisms such as hand operated printers.

One embodiment of the invention enabling the realization of these objects is described in connection with the printer disclosed in the above United States Patent No. 2,922,361 and includes a hand operated shaft so operatively connected to the main drive shaft in such printer that rotation of the hand operated shaft through two revolutions turns the main drive shaft through one revolution putting the printer through a complete cycle. The 2:1 ratio is used to ensure that the several mechanisms in the printer have time to complete their cycles.

The hand operated shaft turns a cam defining a notch which receives a slidably and rockably mounted detent pawl at the end of the second revolution of the hand operated shaft automatically locking the hand operated shaft and thus the drive shaft at the end of a printing cycle. At the end of the first revolution of the hand operated shaft, i.e., at the end of an increment of movement of the hand operated shaft, a pin carried by the drive shaft so latches the slidably mounted detent pawl that it cannot be resiliently urged into the cam notch which is then juxtaposed. However, at the end of two revolutions, the pin has moved out of engagement with the pawl and the pawl is free to be resiliently urged into the cam notch which again is juxtaposed.

The pawl is slidably mounted for movements toward and away from the cam notch and is so formed, arranged and mounted that slight reverse movement of the locked cam followed by forward movement of the cam slides the pawl out of the notch, unlocking the hand operated shaft to start a new cycle.

The cam and part of the cam-engageable end of the pawl are knurled. During forward rotation, the knurled surface of the cam rides freely on the unknurled surface 3,211,020 Patented Oct. 12, 1965 of the pawl. However, should the operator attempt backward rotation of the cam during the printing cycle, the knurled surface on the cam meshes with the knurled surface on the pawl, preventing such backward rotation.

In accordance with the above, one feature of this invention resides in automatically stopping and locking the hand operated shaft after it has been given exactly two revolutions. By means of slight modifications the hand operated shaft is made to stop automatically after being turned through other multiples of a number of degrees. As illustrated, the hand operated shaft can be turned through one revolution without lock up, but is securely locked automatically at the end of two revolutions, i.e., at the end of one complete printing cycle.

Another feature resides in the ease of unlocking the hand operated shaft at the start of a new cycle. The operator merely gives the hand operated shaft a slight reverse movement followed by forward movement to unlock the shaft.

A further feature resides in preventing backward rotation of the hand operated shaft during its forward driving movement.

The above and other objects and features of this invention will be appreciated more fully from the following detailed description when read with reference to the accompanying drawings wherein:

FIG. 1 is a fragmentary elevational view of a weighing scale dial housing showing the location of a hand operated printer as it is mounted on a weighing scale, parts of the dial housing and the printer case being broken away to reveal interior mechanism;

FIG. 2 is an enlarged vertical sectional view taken along the line 2 2 of FIG. 1 showing the mechanism in an operating position different from that shown in FIG. 1;

FIG. 3 is a reduced fragmentary elevational view as seen from a position along line 3-3 of FIG. 2;

FIG. 4 is an exploded view of the mechanism as generally shown in FIG. 2 showing the mechanism in the same operating position as illustrated in FIG. 1;

FIG. 5 is a sectional view generally similar to FIG. 2 showing the mechanism in running position;

FIG. 6 is a sectional view similar to FIG. 5 showing the mechanism being driven in the reverse direction just prior to assuming the running position illustrated in FIG. 5;

FIG. 7 is a sectional view similar to FIG. 5 showing the mechanism in lock up position;

FIG. 8 is an enlarged, detailed view of the mechanism shown in the upper part of FIG. 5;

FIG. 9 is a view of the mechanism as shown in FIG. 8 as positioned an instant later in time;

FIG. l0 is a view of the mechanism as shown in FIG. 8 as positioned when the direction of drive is reversed;

FIG. 11 is a view generally similar to the lower part of FIG. 7 showing a modification; and

FIG. 12 is a view generally similar to the lower part of FIG. 7 showing another modification.

Referring to the drawings, the printer which is disclosed in the above U.S. Patent No. 2,922,361 is shown in FIG. 1 as it is mounted on a weighing scale having a dial housing 20, the printer having a housing 21 and a case 22 which house the same printing mechanism as is disclosed in such patent. The printer `disclosed in the above patent has a main drive shaft which is motor operated. A corresponding shaft 23 shown in FIG. 1 is hand operated, the invention concerning means providing hand operation for the printer, i.e., the invention concerns manually operable means substituted for the motor drive. In certain locations and uses hand operation is neces-sary. The control mechanism of the invention is shown in connection with the printer shaft 23 only for the purpose of illustration, the control mechanism having utility in connection with rotatable shafts in general.

The drive shaft 23 is journaled intermediate its ends in a support 24. Direct hand operation of this shaft is not feasible because the shaft must be turned relatively slowly in order to give the several mechanisms in the printer time to complete their cycles. It has been found that an operator turning the shaft through a handle connected directly thereto tends to turn the shaft so rapidly that the operating parts of the printer jam. Accordingly, a hand operated shaft 25 is provided which is so operatively connected to the drive shaft 23 that rotation of the hand operated shaft Z5 through two revolutions turns the drive shaft 23 through only one revolution putting the printer through one complete cycle. The 2:1 ratio ensures that the mechanisms enclosed in the housing 21 and the case 22 have time to complete their cycles.

The hand operated shaft 25 is journaled at one end 1n a bushing 26 supported by the printer case 22, there being a handle 27 attached to the shaft 25 adjacent such bushing, and is journaled at its other end in a bushing 28 pressed into a vertical support plate 29, a clip 30 retalning the shaft 25 in the bushing 28. The vertical support plate 29 is attached by means of two screws 31 to bosses 32 on the support 24, spacers 33 on the screws 31 separating the support plate 29 from the bosses 32. A second bushing 34 pressed into the support plate 29 provides a bearing surface for the drive shaft 23 which extends through the support plate 29 into the printer case 22. A sprocket 35 is pinned by means of a pin 36 through its hub to the hand operated shaft 25 and a sprocket 37 is pinned by means of a pin 38 (FIG. 3) through its hub to the drive shaft 23, the sprockets being operatively connected through a chain 39. The sprocket 35 and 37 as shown in FIG. 2 are of sizes such as provide a 2:1 drive ratio, i.e., rotation of the hand operated shaft 25 through two revolutions turns the drive shaft 23 through one revolution.

A cam 40 having a notch 41 is pinned to the hand operated shaft 25 by means of a pin 42 through its hub between the hub of the sprocket 35 and the bushing 28. The periphery of the cam 40 is concentric lwith the axis of the hand operated shaft 25. A detent pawl 43 having slot 44 which receives the drive shaft 23 is mounted thereby for sliding action on the shaft 23 for movement toward and away from the cam 40, the cam 40 and the pawl 43 being juxtaposed in the same plane whereby the upper end 45 of the pawl is receivable in the cam notch 41 during a certain orientation of the cam 40. A spring 46 extending between a pin 47 carried by the support plate 29 and the pawl 43 urges the pawl toward the cam 40. The pawl 43 is guided between a pair of guide plates 48 mounted on and held in spaced relationship by two studs 49 carried -by the support plate 29 and has a lower end 50 bent out of the plane of the pawl to -be engageable with a pin 51 extending from the hub of the sprocket 37. The lower end of the pawl is guided between lspacers 52- on the drive shaft 23. Movement of the upper end of the pawl 43 as viewed in FIG. 3 to the right or left is limited by the spaced guide plates 48 and movement as viewed in FIG. 2 to the right or left is limited by spacers 53 (FIG. 4) on the studs 49, clips 54 keeping the left hand one of the guide plates 48 as viewed in FIG. 3 snug against the spacers 53. The upper edge of the upper pawl end 45 has a smooth part 55 and a knurled part 56 (see FIGS. 8-10) and the periphery of the cam 40 is completely knurled at y57 except in an area 58 which is smooth. Smooth area 58 is on the head of an insert 59 carried by the cam 40. Accordingly, the cam 40 is completely knurled except in the area broken by the notch 41 and occupied by the smooth head of the insert 59.

As hereinbefore described, rotation of the hand operated shaft 25 through two revolutions turns the drive shaft 23 through one revolution putting the printer through one complete cycle. This rotation of the hand operated shaft 25 is in a clockwise direction as viewed in FIGS. 2 and 4410. At the beginning of a cycle, the pawl end 45 is received in the cam notch 41 as viewed in FIG. 7, the pawl end 45 being held in the cam notch 41 by the spring 46. Attempted clockwise rotation of the cam 40 fails at this time because the pawl end 45 engages the left hand one of the stop spacers 53 as viewed in FIG. 7, i.e., the cam 40 and, thus, all of the mechanism is locked up.

One of the features of the control mechanism resides in the ease of unlocking the hand operated shaft 25 at the start of a new cycle. The operater merely gives such shaft a slight reverse movement followed by forward movement to unlock the shaft. This is accomplished by turning the cam 40 as viewed in FIG. 7 counterclockwise driving the pawl end 45 against the right hand one of the stop spacers 53, a cam surface 60 on the detent pawl 43 running on such stop spacer and camming the detent pawl 43 downwardly in opposition to the spring 46 into the position shown in FIG. 6 wherein the upper end of the pawl slot 44 engages the printer drive shaft 23. Hence, counterclockwise movement of the cam 40 moves the detent pawl 43 from its position shown in FIG. 7 to its position shown in FIG. 6. The detent pawl 43 is so positioned in FIG. 6 that the lower right hand edge of the smooth part 55 of the upper pawl end 45 cannot be caught in the cam notch 41 when the cam 40 is turned clockwise. Hence, clockwise movement of the cam 40 when the detent pawl 43 is positioned as shown in FIG. 6 causes the knurled surface of the cam 40 to engage the smooth part 55 of the pawl end 45 unlocking the cam and swinging the pawl 43 into its position shown in FIG. 5, i.e., a running position wherein the detent pawl is free of the cam notch. The position shown in FIG. 5 of the cam 40 is the position of the cam after about one and three-quarter turns from the starting position shown in FIG. 7.

The running position of the detent pawl 43 which is shown in FIG. 5 also is shown in the enlarged view, FIG. 8. As shown in FIG. 8, the knurled surface of the cam 40 runs on the smooth part 55 of the upper pawl end 45 as the cam 40 is turned clockwise, the cam 40 driving the upper pawl end 45 toward the left in opposition to the spring 46. However, when the smooth part 55 of the upper pawl end 45 becomes located over the cam notch 41 as shown in FIG. 9, there is no longer contact between the smooth part 55 of the upper pawl end 45 and the cam. If the cam 40 were knurled all around its periphery, the knurled part of the cam and the knurled part 56 of the upper pawl end 45 would mesh at this time. To avoid this, the insert 59 is provided to provide the smooth area 58 on the cam 40 which engages the knurled part 56 of the upper pawl end 45 permitting the cam 40 to continue running on the pawl 43. In FIG. 8, the knurled part of the cam runs on the smooth part of the pawl and, in FIG. 9, the smooth part of the cam runs on the knurled part of the pawl.

Another feature of the control mechanism resides in preventing backward rotation of the hand operated shaft during its forward driving movement. Once the printer cycle is started, it should be continued to completion. This is accomplished as shown in FIG. 10. Reversal of the cam 40 from clockwise to counterclockwise rotation while the detent pawl 43 is in its running position shown in FIG. 8, causes the detent pawl 43 to assume its position shown in FIG. 10 wherein teeth in the knurled portions of the cams 40 and the pawl 43 mesh preventing further rotation of the cam. The detent pawl 43 assumes the position shown in FIG. 10 because the cam 40 when its direction of drive is reversed drives the upper pawl end 45 toward the right, the spring 46 continuously urging the upper pawl end 45 toward the right,

causing clockwise rotation of the pawl 43 about the axis of the drive shaft 23 until the teeth mesh.

A further feature of the control mechanism resides in automatically stopping and locking the hand operated shaft 25 after it has been given exactly two revolutions. The-hand operated shaft is turned through one revolution, i.e., through an increment of movement, without lock up, but is securely locked automatically at the end of two revolutions, i.e., at the end of one complete printing cycle. This is accomplished through the cooperation of the pin 51 and lower pawl end 50. In the lock up position (FIGS. 1, 4 and 7) the pin 51 is remotely positioned relative to the pawl end 50. However, after one revolution of the hand operated shaft 25 the pin 51, which moves as one with the drive shaft 23 that is turned only one-half revolution when the hand operated shaft 25 is turned one revolution, is juxtaposed to the pawl end 50 as shown in FIGS. 2 and 3. In such juxtaposed position, the pin S1 by engagement with the lower pawl end 50 prevents movement of the detent pawl 43 into the cam notch 41 which after one revolution of the cam 40 is in position to receive the upper end of the detent pawl 43. However, after two revolutions of the hand operated shaft 25 the pin 51 returns to its position shown in FIGS. 1, 4, and 7, and the upper pawl end 45 is free to be driven into the cam notch 41 under the action of the spring 46, the cam notch 41 after two revolutions of the hand operated shaft 25 again being in position to receive the upper pawl end 45.

Accordingly, at the start of a printing cycle the upper pawl end 45 is received in the cam notch 41 and the pin 51 is remotely located relative to the lower pawl end 50 as shown in FIGS. 1, 4, and 7. After one revolution of the cam 40, the upper pawl end 45 is prevented from moving into the cam notch 41 by engagement of the pin 51 With the lower pawl end 50 as shown in FIGS. 2 and 3. After two revolutions of the cam 40, the upper pawl end 45 is pulled into the cam notch 41 by the springv 46, automatically stopping the hand operated shaft 25 after it has been given exactly two turns.

By means of slight modifications the hand operated shaft is made to stop after being turned through other multiples of a number of degrees before automatic lock up. For example with reference to FIG. 1l, with a 3:1 l

sprocket ratio, two pins 51a are used instead of the one pin 51 to lallow the hand -operated shaft to be turned through three revolutions While the drive shaft 23a is turned through one revolution before lock up. Reference numbers in FIG. 11 which are similar to those in FIGS. 1-1'0 refer to parts alike in structure and in function. After one revolution of the hand operated shaft, one of the pins 51aby engagement with the lower pawl end 50a prevents lock up, after two revolutions of the hand operated shaft, the other one of the pins 51a by engagement with the lower pawl end 50av prevents lock up, but after three revolutions of the hand operated shaf-t lock up occurs automatically. FIG. 1l illustrates the lock up position.

Similarly, with reference to FIG. 12, with a 4:1 `sprocket ratio, three pins 51b are used to allow the hand operated shaft to be turned through four revolutions while the drive shaft 23b is turned through one revolution before lock up. Reference numbers in FIG. 1-2 which are similar to those in FIGS. 1-11 refer to parts alike in structure and in function. After one revolution of the hand operated shaft, one of the pins Sib by engagement with the lower pawl end 50b prevents lock up, after two revolutions, another of the pins Slb prevents lock up, after three revolutions, the third pin 51b prevents lock up, but after four revolutions of the hand operated shaft lock up occurs automatically. FIG. 2 illustrates the lock up position. Other combinations of sprocket ratios and pins 51b can be used to cause the hand operated shaft to be turned through other numbers of degrees before automatic lock up occurs.

In operation, at the start of a printing cycle the parts of the control mechanism are positioned as shown in FIG. 7. The operator gives the hand operated shaft a slight reverse movement, to position the mechanism as shown in FIG. 6, followed by forward movement to unlock the shaft positioning the mechanism in the running position shown in FIGS. 5 and 8. Should the operator by mistake turn the hand operated shaft in the reverse direction while the mechanism is in the running position, the parts assume the relationship shown in FIG. 10 causing the shaft to be stopped. After one turn of the hand operated shaft, the pin 51 by engagement with the lower pawl end 50 prevents lock up. However, after two turns of the hand operated shaft, the pin 51 no longer obstructs the path of the lower pawl end 50 and automatic lock up occurs.

The embodiment of the invention described in connection with the drawings is to be regarded as illustrative only since the invention is susceptible to variation, modification yand change within the spirit and scope of the appended claims.

Having described the invention, I claim:

1. Control mechanism for rotatable shafts comprising, in combination, a shaft mounted for rotation, automatically operable lock means including a cam mounted to rotate as one with the shaft and defining a notch and a resiliently biased, slidably and pivotally mounted detent finger receivable in the notch for locking the shaft every time that the shaft is turned an increment, and means engageable with the lock means for preventing at least the first locking of the lock means, whereby the shaft is rotatable through more than said increment before lock-up.

2. Control mechanism for rotatable shafts comprising, in combination, a shaft mounted for rotation, automatically operable lock means including a cam mounted to rotate as one with the shaft and defining a notch and a resiliently biased, slidably Iand pivotally mounted detent linger receivable in the notch for locking the shaft every time that the shaft is turned an increment, and means driven by the shaft for preventing at least the first locking of the lock means, whereby the shaft is rotatable through said increment plus at least one more before lock-up.

3. Control mechanism for rotatable shafts comprising, in combination, first and second shafts mounted for rotation and operatively interconnected, automatically operable lock means including a caml mounted to rotate as one with the first shaft and defining a notch and a resiliently biased, slidably and pivotally mounted detent finger receivable in the notch for locking the first shaft every time that such shaft is turned .an increment, and means carried by the second shaft for preventing at least the first locking of the lock means, whereby the first shaft is rotatable through said increment plus at least one more before lock-up.

4. Control mechanism for rotatable shafts comprising, in combination, first and second shafts mounted for rotation, means so operatively interconnecting the shafts that the shafts are rotatable at different rates, automatically operable lock means including a cam mounted to rotate as one with the first shaft and defining a notch and a resiliently biased, slidably and pivotally mounted detent linger receivable in the notch for locking the first shaft every time that such shaft is turned through one revolution, and means carried by the second shaft for preventing at least the first locking of the lock means, whereby the first shaft is rotatable through at least two revolutions before lock-up.

5. Control mechanism for rotatable shafts comprising, in combination, a shaft mounted for rotation, a cam mounted to rotate as one with the shaft and defining a notch, a slidably and pivotally mounted detent finger receivable in the notch for locking the shaft, stop means for limiting pivotal movement of the detent finger, the notch and the detent finger being juxtaposed after every revolution of the cam, resilient means for urging the detent finger toward the cam and into the notch, the cam running on the detent finger during rotation `of the shaft and being rotatable between limits defined by the stop means while the detent finger is in the notch, and means acting in opposition to the resilient means for preventing movement of the detent finger into the notch after at least the first revolution of the shaft, whereby the shaft is rotatable through one revolution plus at least one more before lock-up.

6. Control mechanism for rotatable shafts comprising, in combination, a shaft mounted for rotation, a cam mounted to rotate as one with the shaft and defining a notch, a slidably and pivotally mounted detent linger receivable in the notch for locking the shaft, stop means for limiting pivotal movement of the detent finger, the notch and the detent finger being juxtaposed after every revolution of the cam, resilient means for urging the detent finger toward the cam and into the notch, the cam running on the detent finger during rotation of the shaft and being rotatable between limits defined by the stop means while the detent finger is in the notch, and rotatably mounted pin means acting in opposition to the resilient means and driven by the shaft for preventing movement of the detent finger into the notch after at least the first revolution of the shaft, whereby the shaft is rotatable through one revolution plus at least one more before lock-up.

7. Control mechanism for rotatable shafts comprising, in combination, a shaft mounted for rotation, a cam mounted to rotate together as one with the shaft and defining a notch, a slidably and pivotally mounted detent finger receivable in the notch for locking the shaft, stop means for limiting pivotal movement of the detent finger, the notch and the detent finger being juxtaposed after every revolution of the cam, resilient means urging the detent finger toward the cam and into the notch, the cam running on the detent finger during rotation of the shaft and being rotatable between limits defined by the stop means while the detent finger is in the notch, and means driven by the shaft for preventing movement of the detent finger into the notch after at least the first revolution of the shaft, whereby the shaft is rotatable through more than one revolution before lock-up.

8. Control mechanism for rotatable shafts comprising, in combination, first and second shafts mounted for rotation, means so operatively interconnecting the shafts that the first shaft is rotatable at a rate higher than the second shaft, a cam mounted to rotate as one with the first shaft, and defining a notch, a slidably and pivotally mounted detent finger in the same plane as the cam and receivable in the cam notch for locking the shaft, stop means for limiting pivotal movement of the detent finger, the cam notch and an end of the detent finger being juxtaposed after every revolution of the cam, resilient means for urging the detent finger end toward the cam and into the notch, the cam running on the detent finger end during rotation of the shafts and being rotatable between limits defined by the stop means while the detent finger is in the notch, and pin means driven by the second shaft movable into obstructing position relative to the detent finger after at least the first revolution of the first shaft for preventing movement of the detent finger end into the cam notch after at least the first revolution of the first shaft for preventing vmovement of the detent finger end into the cam notch after at least the first revolution of the first shaft, whereby the first shaft is rotatable through one revolution plus at least one more before lock-up.

9. Control mechanism for rotatable shafts comprising, in combination, a shaft mounted for rotation, a cam mounted to rotate as one with the shaft and defining a notch, a slidably and pivotally mounted detent finger having an end receivable in the notch for locking the cam and the shaft, stop means limiting pivotal movement of the detent finger, a cam surface on the detent finger engageable with the stop means and a running surface on the detent finger end engageable with the cam, the cam notch and the detent finger end being juxtaposed after every revolution of the cam, and resilient means urging the detent finger end toward the cam, the cam running on the running surface of the detent finger end when the cam is unlocked, slight reverse movement of the locked cam followed by forward movement unlocking the cam and the shaft, Isaid reverse movement of the locked cam driving the cam surface on the detent finger against the stop means camming the detent finger end partly out of the cam notch and said forward movement following said reverse movement of the locked cam by engagement of the cam with the running surface on the detent finger end camming the detent finger end the rest of the way out of the cam notch.

10. Control mechanism for rotatable shafts comprising, in combination, a shaft mounted for rotation, a cam mounted to rotate as one with the shaft, the cam dening a notch an-d having a running direction, the cam being knurled except in a relatively small smooth part adjacent the notch in the running direction from the notch, a slida` bly and pivotally mounted detent finger having an end with a surface partly knurled and partly smooth receivable in the cam notch for locking the cam and the shaft, stop means limiting pivotal movement of the detent finger, the cam notch and the detent finger end being juxtaposed after every revolution of the cam, and resilient means urging the detent finger end toward the cam, the knurled part of the cam running on the smooth surface of the detent finger end and the smooth part of the cam running on the knurled surface of the detent finger end in opposition to the resilient means when the cam is unlocked and rotated in the running direction, attempted reverse rotation of the cam aiding the resilient means pivot the detent finger until the knurled part of the cam meshes with the knurled surface of the detent finger end stopping such reverse rotation.

References Cited by the Examiner UNITED STATES PATENTS 710,593 10/02 Medley.

711,151 10/02 Dement et al 74-527 X 1,645,136 10/27 Goldsmith et al. 192-8 2,178,066 10/39 Clark.

2,213,101 8/40 Coil.

2,427,992 9/47 Knauer 192-8 X 2,758,170 8/56 Jordon 200-67 2,770,136 11/56 Vervest et al. 7410.2 2,972,258 2/ 61 Vervest et al 74-l0.2 2,995,225 8/61 Cline 192-8 2,995,226 8/61 Gilder 192-8 3,012,447 12/61 Wallace 74-l0.2 X

FOREIGN PATENTS 538,027 3/57 Canada.

717,743 2/42 Germany.

128,309 5/50 Sweden.

BROUGHTON G. DURHAM, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noc 3,211,020 October l2, 1965 Clarence Eo Adler It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

f-; column 6,

Column 5, line 7l, for "Z" read rl2 line 29, for "lock means" read finger Signed and sealed this 19th day of July 1966c (SEAL) Attest:

ERNEST W. SWIDER Attesting Officer EDWARD J. BRENNER Commissioner of Patents 

7. CONTROL MECHANISM FOR ROTATABLE SHAFTS COMPRISING IN COMBINATION, A SHAFT MOUNTED FOR ROTATION, A CAM MOUNTED TO ROTATE TOGETHER AS ONE WITH THE SHAFT AND DEFINING A NOTCH, A SLIDABLY AND PIVOTALLY MOUNTED DETENT FINGER RECEIVABLE IN THE NOTCH FOR LOCKING THE SHAFT, STOP MEANS FOR LIMITING PIVOTAL MOVEMENT OF THE DETENT FINGER, THE NOTCH AND THE DETENT FINGER BEING JUXTAPOSED AFTER EVERY REVOLUTION OF THE CAM, RESILIENT MEANS URGING THE DETENT FINGER TOWARD THE CAM AND INTO THE NOTCH, THE CAM RUNNING ON THE DETENT FINGER DURING ROTATION OF THE SHAFT AND BEING ROTATABLE BETWEEN LIMITS DEFINED BY THE STOP MEANS WHILE THE DETENT FINGER IS IN THE NOTCH, AND MEANS DRIVEN BY THE SHAFT FOR PREVENTING MOVEMENT OF THE DETENT FINGER INTO THE NOTCH AFTER AT LEAST THE FIRST REVOLUTION OF THE SHAFT, WHEREBY THE SHAFT IS ROTATABLE THROUGH MORE THAN ONE REVOLUTION BEFORE LOCK-UP. 